That may well be the case that the permissions are correct on other sites, but the permissions are site-specific to the files and folders of each site.

Providing the FPA report will help us determine anything else that might be incorrect: https://forumpostassistant.github.io/docs/ (goes further in-depth with the system info than what you have already provided; see red box (top of screen), "Forum Rules")

Regards,
--------------------------------------------------------------A Murray
Millennium Falcon - it's the ship that made the Kessel run in less than 12 parsecs! The fastest hunk of junk in the galaxy.

I am not a Joomla beginner, I started with Mambo and have built a lot of Joomla websites since the beginning of Joomla, but I have not encountered this problem before.
I can assure you that it is not due to the permissions.
The site worked flawlessly for years, but somewhere something must have gone wrong and I can't figure out what.

But here is the FPA report.
Note: the sourcerer error has nothing to do with the problem, when I disable the sourcerer plugin the problem remains.

LiveSite in the FPA results comes from the variable $live_site in the file configuration.php and it should be empty. The value was used in the past by some third party extensions.

Write enable the file configuration.php, edit it and change the level of error reporting from 'none' to 'maximum'. Enable the Debug mode, too, then save the file and go to Global Configuration to see if you get error messages when saving the configuration from the back end.

The attached FPA results show that Error Reporting in PHP has been set to 32767, meaning absolutely everything was to be reported, but in Joomla the level of error reporting 'None' in Global Configuration nullifies the PHP setting.

I have seen some older third party plugins deliberately turn off error reporting and leave it that way, which may allow the plugin to run in later versions of PHP but also interferes with troubleshooting.

Even with $error_reporting set to maximum the FPA report is the same and no errors appear in the administrator. there are only errors on the website not in the administrator only a kazaam warning when I unpublished an article.